Conventionally, there is a wireless control system including a controlled apparatus and a wireless controlling apparatus that controls the controlled apparatus via a wireless communication path. For example, the wireless controlling apparatus recognizes the controlled apparatus. After the recognition, information such as an identifier is exchanged between the wireless controlling apparatus and the controlled apparatus. In a state where the information exchange has already been performed, the wireless controlling apparatus transmits a command to the controlled apparatus. Upon receiving the command, the controlled apparatus operates according to the command. In other words, in the wireless control system, one of the wireless controlling apparatus and the controlled apparatus recognizes the other apparatus, that is, one of the wireless controlling apparatus and the controlled apparatus detects the other apparatus. After this recognition, information such as an identifier is exchanged between the wireless controlling apparatus and the controlled apparatus in the wireless control system. This information exchange enables data communication between the wireless controlling apparatus and the controlled apparatus in the wireless control system. After the information exchange, data communication is performed in the wireless control system, where the wireless controlling apparatus transmits a command to the controlled apparatus and the controlled apparatus receives the transmitted command. The controlled apparatus then operates according to the received command. Note that the recognition mentioned above means that the controlled apparatus is detected simply as a target to be controlled by the wireless controlling apparatus, in a state where actual data communication with the wireless controlling apparatus is still impossible.
Conventionally, a controlling apparatus that remotely controls a controlled apparatus such as a TV, namely, a remote control, transmits a command using infrared radiation. In recent years, attention is given to control via a wireless communication path of radio waves instead of infrared radiation.
Since the wireless communication path of radio waves typically does not have directionality, usually the controlled apparatus and the remote control each register an ID of the other apparatus and respond only to a packet having the registered ID, in order to avoid interference with a neighboring apparatus of the same type. This ID exchange/registration is called pairing. A MAC address is typically used as the ID.
A method of the ID exchange is described below. The controlled apparatus and the remote control are each provided with a switch for exchanging IDs. To perform pairing, the user presses the switches on the controlled apparatus and the remote control approximately at the same time.
When the switch on the controlled apparatus is pressed, the controlled apparatus transmits a remote control search packet including a MAC address of the controlled apparatus, by broadcasting.
When the switch on the remote control is pressed, the remote control enters a remote control search packet reception wait state. Upon receiving the remote control search packet, the remote control returns a response including a MAC address of the remote control, to the MAC address of the controlled apparatus included in the packet. Thus, the MAC addresses are exchanged.
There is also a situation where one remote control controls a plurality of controlled apparatuses. In such a case, the user performs ID exchange between the remote control and each controlled apparatus to be controlled by the remote control from among the plurality of controlled apparatuses. Take a remote control that controls a TV and a Digital Video Recorder (DVR) as controlled apparatuses, for example. The remote control includes keys for controlling the TV such as channel change keys, keys for controlling the DVR such as a play key and a fast forward key, and also switch keys for switching the control between the TV and the DVR and arrow keys for controlling a GUI displayed on the TV. By switching the operated apparatus using the switch keys provided on the remote control, the user can operate the TV and the DVR with one remote control (for example, see Patent Reference 1).
Moreover, there is the following pairing method. A controlling apparatus communicates with a desired controlled apparatus using infrared radiation having directionality, thereby specifying the controlled apparatus. Subsequently, the controlling apparatus communicates with the controlled apparatus using a wireless communication path of radio waves (for example, see Patent Reference 2).    Patent Reference 1: Japanese Unexamined Patent Application Publication No. 9-504420    Patent Reference 2: Japanese Unexamined Patent Application Publication No. 2001-258082